Flower:

Branching cluster at the top of the stem, 2 to 10 inches long with 1 or 2 branches per node. Sometimes the lower branches are enclosed by the uppermost leaf sheath. Branches are 2¼ to 6 inches long, initially erect becoming spreading to drooping, each with 1 to 3 branchlets that are congested at the branch tip and remain more or less appressed to the branch. Spikelets (flower clusters) are arranged all on one side of a branchlet, appressed, much overlapping. Spikelets are short-stalked, broadly oval to nearly round in outline with a single floret.

A pair of bracts (glumes) at the base of a spikelet is absent altogether. Surrounding a floret are a pair of bracts (lemma and palea), both boat-shaped, whitish with green veins, 4 to 5.5 mm (1/8 to ¼ inch) long and flattened laterally with conspicuous bristly hairs along the keels, so the spikelet appears fringed all around the outer edge. The lemma is about 2/3 the width of the spikelet, 5-veined, with a few hairs along the edges and veins. The palea is about 1/3 the width of the spikelet and 3-veined.

Leaves and stems:

Leaves are 2 to 14 inches long, 1 to 2 cm (3/8 to ¾ inch) wide, flat, somewhat floppy, smooth and hairless to softly hairy or slightly rough textured on both surfaces, and usually rough along the edges from short, stiff hairs.

The sheath is smooth to sparsely rough hairy, often short hairy on the back and/or front where it meets the blade, and often has a pair of small triangular lobes (auricles) at the apex. The ligule (membrane where the leaf joins the sheath) is .5 to 1.5 mm long, mostly straight across, not fringed with hairs, and joined to the sheath auricle. Nodes are densely hairy with downward pointing (retrorse) hairs. Stems are hairless to sparsely rough hairy, unbranched. Plants may form loose colonies from long, scaly rhizomes.

Fruit:

Spikelets turn dark brown at maturity, the florets shedding individually as each grain matures, leaving a naked stem behind. Grains (seeds) are reddish-brown, elliptic, 3.5 to 4 mm long.

Notes:

Leersia lenticularis is a rare species of floodplain forest and reaches the northern tip of its range in southeast Minnesota. According to the DNR, it and other floodplain species along the Mississippi River are at risk primarily from interruptions to natural water level cycles due to controlled shipping traffic, degraded water quality from upstream pollution, and a host of invasive species, Reed Canary Grass (Phalaris arundinacea) in particular. Only 2 locations from the early 1900s were known until biological surveys were conducted starting in the 1970s, then only a handful of additional populations were found. Listed as a Special Concern species in 1984, it was elevated to Threatened in 2013. While from a distance, Leersia lenticularis may resemble other grasses with a few-branched panicle, such as Glyceria borealis (Northern Manna Grass), a closer inspection of the spikelets shows how different the Leersia species are: the single-flowered spikelets, lacking awns and flattened laterally, with conspicuous hairs along the keel of both lemma and palea, along with the absence of glumes are a unique combination, and all 3 Minnesota Leersia species also have densely hairy stem nodes. Leersia lenticularis is distinguished from the other 2 Leersia species by the nearly round spikelet, where the others are distinctly longer than wide.